1) From PG 15 onward, the datlastsysoid has been removed from the table pg_database.
We have added the constant _DATABASE_LAST_SYSTEM_OID = 16383, all the objects below
this value are considered to be system objects. Modified the pgAdmin logic accordingly.
2) Concatenation operator '||' needs a specific typecast to be applied to query variables. Modified SQL's accordingly.
Fixes#7283
Along with this, I have also fixed few other issues/icons found on the way:
1) Dependencies tab for inherited tables/foreign keys shows partial text (Fixes ##3994).
2) Dependencies tab for child partition table shows parent partition table as Function.
3) Dependencies tab for triggers shows trigger functions as plain functions.
4) Dependents tab for partitioned table shows the child partition tables as normal table instead for partitioned tables.
2) Add Unit Tests for each file.
3) Add ORDER BY into Copy Selection Feature test to ensure the results are retrieved always in the same order
4) Renamed the Scenario of the xss_checks_pgadmin_debugger_test and skip it for versions less than 9.1
5) Deleted unused __init__.py files.
